The present invention relates in general to a clinical testing apparatus. More particularly, this invention pertains to a testing apparatus for making multiple sample clinical determinations of ionized calcium concentrations or other ions in body fluids.
My copending application Ser. No. 320,264 shows a testing apparatus providing these multiple samplings. Although this apparatus operates quite satisfactorily it is an object of the present invention to provide an improved clinical testing apparatus which is preferably for making multiple sample clinical determinations of original ionized calcium concentrations of body fluids.
Another object of the present invention is to provide an improved turntable type apparatus for performing a multiple sampling.
A further object of the present invention is to provide an improved cup construction for containing the fluid samples.
Still another object of the present invention is to provide a programmable cup construction operative in conjunction with sensor means to control operation at the probe station such as by controlling the introduction of an alternative gas at the probe station.
The preferred testing apparatus is for making multiple sample clinical determinations of original ionized calcium concentrations of body fluids taken from a body. This apparatus comprises a rotatable turntable for removably carrying a plurality of body fluid sample containers or cups preferably having upwardly facing container mouths. The rotatable turntable is defined by a plurality of radially extending leaves supported in a cantilever fashion and thus fixed in position at one end along a circular locus. A cover is positioned over the turntable to substantially close the container mouths while permitting rotational movement of the turntable with respect to the cover. Means are providing for rotating the turntable with respect to the cover at predetermined time intervals to advance each of the containers to successive stations and eventually to the probe station. Each leave flexes downwardly thus permitting the cup to be inserted on the leaves and in intimate contact with the bottom surface of the cover. In the disclosed embodiment the leave has at its free end an erect post of partially spherical shape that engages with a frusto-conic cavity in the base of the cup or container The gas means including a plenum chamber in the cover pass a gas such as a water saturated carbon dioxide gas to each of the cups at predetermined stations about the cover. The cover has associated therewith a probe assembly comprising one or more probes which are selectively and sequentially registered with the cups.
In accordance with the present invention the cups may be constructed in different sizes or top configurations with the size of the cups functioning to program one or more operations of the apparatus. For example, when a regular cup is used the outlet jets from the cover pass the gas into the cup at a suitable velocity to produce a mixing action of the fluid in the cup. Alternatively, if a cup with a smaller inside diameter is selected the mixing hole is then blocked thereby preventing mixing of the contents in the cup. In still another embodiment also having a smaller inner diameter the cup may be provided at its mouth with an annular channel or tunnel communicating with the mixing hole and including a vent in the cup from the tunnel for venting the gas or an additional hole in the cover for coupling this positive pressure to a signalling device or permitting the introduction of an alternative gas, for example, into the cup at the probe station.
In still another embodiment there may be provided one or more additional holes which are sensor holes and are positioned to be at all times external to the internal diameter of any cup that may be used. These holes do not permit gas transit for the purpose of mixing but rather are for the purpose of sensing. The purpose of the first sensor hole is to permit introduction of an alternate gas, different from the gas in the plenum chamber of the cover to the probe station cup. When a normal cup is used the alternative gas is vented through this sensor hole. However, when the hole is blocked by means of a cup with a wide mouthed flange the gas seeks an alternative route which may be provided for by a flexible conduit leading to a mixing hole mounted within the confines of the probe holder, thus introducing this alternate gas into the cup disposed at the probe station. The second sensor hole may be disposed radially outside of the first sensor hole and may be used to provide a signal which can be used for many different purposes but is commonly used to identify the fact that the cup contains a standard to be used for automatic electrode calibration. This indication is achieved in a similar manner to that discussed with reference to the first sensor except that the alternative route may lead to a pressure switch for generating a desired electrical signal.
In accordance with another aspect of this invention there is provided a heating means in association with the cover and associated plenum chamber. The gas which hits the sample liquid in the cup is required to be both at the same temperature as the sample itself and also fully saturated with water vapor at that temperature. The heating means provides heat which is conducted and radiated to the cups and sample. The plenum chamber is preferably heated slightly above the temperature of the saturated entering gas which temperature is the same as the intended temperature of the sample at the time of measurement. It has also been found that having the plenum temperature slightly raised prevents condensation in the plenum of the cover. When the gas is then exited through the jets from the plenum chamber the decrease in pressure causes a decrease in temperature to the desired temperature and at the same time the gas is again fully saturated as its exits at essentially atmospheric pressure into the cup.